Asteroids have at least one advantage over planets - their shallow gravity well makes it much easier to come and go. Perhaps a little too easy. The sci-fi vision of a travel/trade network in space seems more feasible between asteroids than between planets.
The question is what one would trade, especially if there has to be an actual early growth phase rather than just having it poofed into existence with regional value-added manufacturing specialties out of nowhere.
Precious industrial metals and beamed solar power would be one thing.
Spaceborne agriculture would be another, if only for species like bananas which are too vulnerable to parasites on Earth now (easier sterile, isolated environments).
> Precious industrial metals and beamed solar power would be one thing.
I think you're dramatically underestimating the distances involved to the asteroid belt.
Beaming power over one to two astronomical units is something in between impractical and a death-ray superlaser. (And that's assuming Earth is exporting the energy, because the other way around makes even less sense--the asteroid belt only gets 10 to 20% as much light.)
> bananas
Lastly, sterile environments on Earth will be wayyy easier and cheaper an equivalent facilities in orbit, to construct, maintain, and house a workforce, etc.
The problem of screening/cleaning everything that passes through the airlock is the same regardless of gravity.
> Lastly, sterile environments on Earth will be wayyy easier and cheaper an equivalent facilities in orbit
Not when you’re competing with belters growing truck sized GMO bananas in massive inflatable aeroponic spheres with 24 hours of lensed daylight and a robotic workforce that only needs tiny motors and propellors to move around. Not to mention the savings on freeze drying and sterilizing the crops before transit, they aren’t selling the water back at those prices!
Again, that has a whole bunch of practicality plot-holes, as if you're throwing interesting scenes against the wall to see what sticks like zero-G spaghetti.
Everything you've described could be accomplished better closer to home, such as with a sun-synchronous orbit [0] or at most of the local Lagrange points.
Insanely better on solar light supply, emergency resilience, incoming essential goods and staff, and most importantly your gigantobanana might still be edible by the time it reaches anybody else. (Without spending ridiculous amounts on fuel or transit times of over a year.)
